Question

What is space-time expansion​

Answer 1

The expansion of the universe is the increase of the distance between two distant parts of the universe with time. It is an intrinsic expansion whereby the scale of space itself changes. ... To an observer it appears thatspace is expanding and all but the nearest galaxies are receding into the distance.

Answer 2

Answer:

The expansion of the universe is the increase of the distance between two distant parts of the universe with time. It is an intrinsic expansion whereby the scale of space itself changes. ... To an observer it appears that space is expanding and all but the nearest galaxies are receding into the distance.